The invention relates to attachable coupings for hose, but more particularly, the invention predominately relates to ferrules of the crushable type.
Hose ferrules may be categorized by the way they function when they are coupled to a hose. There are three general categories or types of ferrules: "undeformed," "expandable," and "crushable." The "undeformed" ferrule variety is not required to change dimensions when used as part of a hose coupling. The ferrules may be adhesively bonded to a hose end, vulcanized to a hose end, or have internal threads and threaded to a hose end. Such ferrules are usually machined from wrought bar stock materials or they are cast and subsequently machined in several places. The ferrules may be used in both high and low hose pressure applications (e.g., pressures from 25 psi to 20,000 psi).
"Expandable" type ferrules are usually stamped from flat sheet stock or stamped tubing. The ferrules are used in low pressure applications (e.g., below 200 psi) such as for garden hose. The ferrules are expanded in the coupling process as a tool that is inserted in the bore of a coupling stem and expanded radially outwardly against the hose wall and in turn against the ferrule. The ferrule slightly expands as the hose is pinched between the stem and ferrule. The ferrule material must withstand the radial expansion without fracturing. For example, garden hose ferrules made of soft brass have an elongation of 30-50 percent where the elongation is considered as a measure of reformability or malleability of the brass ferrule.
Ferrules of the "crushable" type are usually turned from wrought bar stock or drawn from tubing. Such ferrules must have sufficient malleability so as not to fracture when they are crushed such as by crimping or swaging to reduce their circumference by 20 percent or more. Many such ferrules are made from mild steel having an ultimate tensile strength of 65,000 psi and a tensile elongation of 25 percent or more. Again, tensile elongation is an indicator of malleability. The ferrules may be used in both low and high pressure hose applications (e.g., hose pressures up to 20,000 psi depending on hose diameter).
Powdered metal parts are made by pressing metal powder to a desired shape forming a briquette or green part that is later heated and sintered to form a finished part. Powdered metal parts are limited in scope to shapes that may be suitably pressed, and to some physical properties that are substantially lower than parts formed of wrought material. Generally speaking, the powdered metal process offers the advantage of good dimensional control, reduction in or elimination of machining, and substantially the elimination of waste material. Sometimes, powdered metal parts are resized by coining to obtain dimension stability or to increase density and tensile strength. However, ferrous powdered metal parts are seldom, if ever, considered for applications requiring deformation because powdered ferrous metal (e.g., plain iron) exhibits tensile elongation of only about 9 percent at a relatively high compacted powder density (e.g., 89 percent of a theoretical 100 percent). Elongation falls off sharply to about 2 percent at densities of about 75 percent of theoretical. Comparatively, wrought mild steel has a tensile elongation commonly exceeding 30 percent.
Powdered metal parts are usually made to their "in-use" configuration. Some parts may require reconfiguring by removing metal. Heretofore, powdered metal parts were not adaptable for being significantly reconfigured from their sintered shape with part deforming such as by bending, swaging or drawing because of their inherently poor malleability.
This invention is primarily directed to crushable type ferrules. However, an advantage of the invention is that ferrules of the "undeformed" and "internally expandable" type may also be produced.